Selective Titanium Sidewall Control in Deep Trench Vias
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Solution Overview
Problem
Deep trench vias in integrated circuit (IC) devices cause undesirable shifts in threshold voltages of transistors, known as the deep trench via proximity effect, which is a challenge in backside power delivery systems.
Innovation Solution
Implementing selective titanium deposition during metallization of deep trench vias and source/drain contacts to reduce or eliminate titanium on the sidewalls of these structures, using techniques that allow precise deposition on specific areas while avoiding deposition on others.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If deep trench vias are used for backside power delivery, then power routing complexity is reduced and fabrication is simplified, but transistor threshold voltage shifts occur due to proximity effects
Solution Approach 1:
The patent removes the harmful titanium material from the sidewalls of deep trench vias through selective etching processes. This extraction eliminates the source of the proximity effect that causes threshold voltage shifts in nearby transistors, while preserving the beneficial backside power delivery architecture.
Solution Approach 2:
The patent applies different material compositions to different regions of the via structure. Titanium is selectively deposited only on the bottom of the via where it provides beneficial adhesion and conductivity, while the sidewalls are either left without titanium or treated with a different material composition to avoid the proximity effect.
2Strength
If titanium is deposited on sidewalls of deep trench vias, then adhesion and conductivity are improved, but proximity effects cause threshold voltage shifts in transistors
Solution Approach 1:
The patent implements spatially selective titanium deposition where titanium is applied only to specific regions (bottom of vias) that require adhesion and conductivity enhancement, while excluding areas (sidewalls) that would cause proximity effects on transistors.
Solution Approach 2:
The via structure is divided into functional zones: the bottom region receives titanium for adhesion and conductivity, while the sidewall region is either left untreated or receives a different material composition to prevent harmful interactions with adjacent transistors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach mitigates the deep trench via proximity effect by reducing or eliminating titanium on sidewalls, thereby minimizing the impact on transistor threshold voltages and improving the performance of backside power delivery systems.
Implementation Method 1
selective titanium deposition during metallization of deep trench vias and source/drain contacts
Data Source
AI summary
Disclosed herein are IC structures and devices that aim to mitigate proximity effects of deep trench vias. An example IC structure may include a device region having a first face and a second face, the second face being opposite the first face, and further include a conductive via extending between the first face and the second face, wherein the conductive via includes an electrically conductive material, and wherein a concentration of titanium at sidewalls of the conductive via is below about 1015 atoms per cubic centimeter.